package org.dut.community.service;

import org.dut.community.entity.User;
import org.dut.community.util.CommunityConstant;
import org.dut.community.util.RedisKeyUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataAccessException;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.SessionCallback;
import org.springframework.stereotype.Service;

import java.util.*;

@Service
public class FollowService implements CommunityConstant {
    @Autowired
    private RedisTemplate redisTemplate;
    @Autowired
    private UserService userService;

    /**
     * 关注
     * @param userId 关注者
     * @param entityType 实体类型
     * @param entityId 实体id
     */
    public void follow(int userId, int entityType, int entityId) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                operations.multi();
                operations.opsForZSet().add(followeeKey,entityId,System.currentTimeMillis());
                operations.opsForZSet().add(followerKey,userId,System.currentTimeMillis());
                return operations.exec();
            }
        });
    }

    /**
     * 取消关注
     * @param userId 关注者
     * @param entityType 实体类型
     * @param entityId 实体id
     */
    public void unfollow(int userId, int entityType, int entityId) {
        redisTemplate.execute(new SessionCallback() {
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                operations.multi();
                operations.opsForZSet().remove(followeeKey,entityId);
                operations.opsForZSet().remove(followerKey,userId);
                return operations.exec();
            }
        });
    }

    /**
     * 查询 用户关注的 followee的数量
     * @param userId 关注者
     * @param entityType 实体类型
     * @return
     */
    public long findFolloweeCount(int userId, int entityType) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().size(followeeKey);
    }
    /**
     * 查询 关注了该实体的 粉丝（follower）的数量
     * @param entityType 实体类型
     * @param entityId 实体id
     * @return
     */
    public long findFollowerCount(int entityType, int entityId) {
        String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
        return redisTemplate.opsForZSet().size(followerKey);
    }

    /**
     * 查询 用户是否关注了该实体
     * @param userId 关注者
     * @param entityType 实体类型
     * @param entityId 实体id
     * @return
     */
    public boolean isFollowed(int userId, int entityType, int entityId) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().score(followeeKey,entityId) != null;
    }
    /**
     * 查询 用户关注的 followee，用于页面展示
     * @param userId 关注者
     * @param offset 偏移量
     * @param limit 限制数量
     * @return
     */
    public List<Map<String,Object>> findFollowees(int userId, int offset, int limit) {
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId,ENTITY_TYPE_USER);
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followeeKey, offset, offset+limit-1);
        if(targetIds == null || targetIds.isEmpty()) {
            return null;
        }
        List<Map<String,Object>> list = new ArrayList<>();
        for(Integer targetId : targetIds) {
            Map<String,Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user",user);

            // 得到秒数，转化为标准时间
            Double score = redisTemplate.opsForZSet().score(followeeKey,targetId);
            map.put("followTime",new Date(score.longValue()));
            list.add(map);
        }
        return list;
    }
    /**
     * 查询 关注了该实体的 粉丝（follower），用于页面展示
     * @param userId 关注者
     * @param offset 偏移量
     * @param limit 限制数量
     * @return
     */
    public List<Map<String,Object>> findFollowers(int userId, int offset, int limit) {
        String followerKey = RedisKeyUtil.getFollowerKey(ENTITY_TYPE_USER,userId);
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followerKey, offset, offset+limit-1);
        if(targetIds == null || targetIds.isEmpty()) {
            return null;
        }
        List<Map<String,Object>> list = new ArrayList<>();
        for(Integer targetId : targetIds) {
            Map<String,Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user",user);

            // 得到秒数，转化为标准时间
            Double score = redisTemplate.opsForZSet().score(followerKey,targetId);
            map.put("followTime",new Date(score.longValue()));
            list.add(map);
        }
        return list;
    }

}
